The vertical coordinate has nothing to do with ball motion. It's an anomaly. The longer the thumb stays in the ball, the more the vertical coordinate is up. In full rollers, in which the thumb stays in the ball the longest, the vertical coordinate is usually 2+" up.

Follow the instructions and start with the center of the grip as the center of the inserts. Measure from there through the pin. Measure 10" on that line. Make sure the center of the MOtion Hole is at least 1 1/4" for the 1st oil ring on the bottom of the ball. Start small. There can be NO thumb hole in the ball if you use a balance hole under the revised rules.

Plugging and re-drilling a ball is specific to each event. The amount of change is related to which part of the ball (inner core, outer core, or shell) the holes hit. The changes are almost always minimal.

Regarding a dual angle layout to match the reaction from the Rico layout:

[color=#FFFF00]Rico's are vague depending on PAPs, but my suggestion is 15 / 5 / 50 with a P4 hole for symmetricals. I wouldn't do it on an asym. because regular "Dual Angle" layouts are so precise and accurate for asyms.[/color]

Taken from: posting.php?mode=quote&f=15&p=84937 (see #20)It compares a sym. vs. an asym., both drilled 3 3/4" by 30*. The change in core angle in the asym. is much greater than the change in core angle of the sym. This means that the core of the asym. lays down more and faster than the core of the sym. contributing to the sharper, quicker revving breakpoint of the asym. ball.

In regards to this remark : Also the pro shop just wants to put the cg center and just below fingers and then just set the pin to pap without drilling a thumb. Is this an ok method or is it very imprecise?

That's a good method. I just recommend pin to PAP distances between 4 1/2" and 5 1/4". Closer to 4 1/2" to get the ball to corner and closer to 5 1/4" for smoother roll.

about Motion hole with fingers only (no thumb layout) from post: posting.php?mode=quote&f=13&p=85581I haven't investigated that yet. The MOtion Hole ball reaction results from the combined effect of the thumb hole and the MOtion Hole. So, I'm not sure.

about Motion hole with fingers only (no thumb layout) from post: posting.php?mode=quote&f=13&p=85581I haven't investigated that yet. The MOtion Hole ball reaction results from the combined effect of the thumb hole and the MOtion Hole. So, I'm not sure.

Follow the instructions and start with the center of the grip as the center of the inserts. Measure from there through the pin. Measure 10" on that line. Make sure the center of the MOtion Hole is at least 1 1/4" for the 1st oil ring on the bottom of the ball. Start small. There can be NO thumb hole in the ball if you use a balance hole under the revised rules.

Time to understand the effect of both cores and covers on the ball gooing down the lane. It's a sliding scale. The closer to the foul line the ball is, the more the coverstock (including surface) dominates. The closer to the ball going off the pin deck, the more the core dominates. In the pin deck (going thru the pins), the cover is mostly insignificant. In the heads (the front of the lane), the core is mostly insignificant. As the ball travels down the lane the coverstock becomes less important and the core becomes more important. Hitting the pocket is mostly related to to the coverstock, but pin carry is mostly related to ball dynamics (core).

1) Please the pin (low RG axis),past the VAL.2) Place the low RG axis of the drilled ball (post drilling low RG axis) more than 6 3/4" from the bowler's PAP. Because of the movement of the low RG axis after drilling, I use 5 3/4" pin to PAP as max.

Drilling high track bowlers with pin to PAP distance > 4 3/4" can pull the track up on the holes, but won't reverse the flare until you exceed 5 3/4".

Balance hole size and location is the most critcal factor to ball motion on a symmetrical ball because it moves the PSA of the drilled ball around so much. On no thumb drillings, the balance hole can cause wild swings in the PSA location because the drilling holes remove so little mass from the ball. I recommend drilling the finger holes at least 3" deep on no thumb balls to help stabilize PSA movements when adding a balance hole. I've been tracking the movement of the PSA on no thumb balls with a DeTerminator to learn more about the PSA movement. No solid determinations, yet. My 13 year old son, Levi, is a no thumb bowler because I wouldn't let him use his thumb when he started. So I get plenty of practice on these layouts.

Taken from: viewtopic.php?t=845 (see #9)"Interchangeable thumbs are an important part of ball drilling today. We included demos on both the Vise IT and the Turbo Switch Grip in our advanced class this year. Both systems work well when installed properly and DO NOT negatively affect ball dynamics. USBC Equip. and Specs. did a study to prove that they don't negatively affect ball dynamics."

Let's do some confirming of the measurements. Put a piece of tape on your measured PAP and see if the ball rotates about that PAP as it hits the lane. You'll have to have someone watch it as the tape will move as the ball flares. Another way to confirm the PAP is to find the center of the ball track and measure 13 1/2" from that in any direction to find the PAP. I use that method when an Armadillo is not available.

A ball "burns up" when it enters the roll phase too soon. When the axis rotation and the axis tilt are equal (the 2nd transition), the ball will no longer hook. If the ball still has a little axis rotation and tilt (which are then equal), it will still hit. The ball will only stop hitting when both the axis rotation and tilt equal zero (true "roll out").

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